A technology used for control of display of multiple overlapping windows is described in Japanese Patent Application No. JP H08-161139A, published on Jun. 21, 1996 to Mitsubishi Electric Corp. According to the description in JP H08-161139A, when at least two windows are displayed on a display screen such portions of the windows overlap, a window displayed in the foreground is interchanged with a window(s) displayed in the background at predetermined time periods. A length of time for which respective windows are displayed in the foreground is dependent upon a length of time for which a particular window is used.